When doing module = types.ModuleType('mymodule'), we don't get any chance of doing further customization, and we can't override module.__dict__ since it's readonly...
The same seems to apply with all other importlib functions (module_from_spec alike)
Is there a way of doing it which is not too much dirty (like... sub-classing ModuleType, and creating a temporary module and copying the fields...) ?
You can create a proxy module that delegates attribute access to a separate mapping:
from types import ModuleType
def custom_mapping_module(name, mapping):
class _CustomMappingModule(ModuleType):
def __getattr__(self, name):
return mapping[name]
def __setattr__(self, name, value):
mapping[name] = value
def __delattr__(self, name):
del mapping[name]
return _CustomMappingModule(name)
so that as an example:
from collections import ChainMap
c = ChainMap({'a': 1}, {'b': 2})
m = custom_mapping_module('foo', c)
print(m.a) # outputs 1
print(m.b) # outputs 2
del m.a
m.b = 3
print(m.b) # outputs 3
print(c) # outputs ChainMap({'b': 3}, {'b': 2})
print(m.__name__) # outputs foo
print(isinstance(m, ModuleType)) # outputs True
